Post on 01-Jan-2016
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Human Memory
It is good to have an end to journey towards; but it is the journey that matters, in the
end.Ursula K. Le Gui
Memory
• Process by which information is:– Acquired
• Encoding
– Stored in the brain• Storage
– Later retrieved• Retrieval
– Eventually (possibly) forgotten
Information-Processing Model of Memory
• Computer as a model for our memory
• Three types of memory– Sensory memory– Short-term memory (STM)– Long-term memory (LTM)
• Can hold vast quantities of information for many years
Information-Processing Model of Memory
Short-termmemoryStimulus
Sensorymemory
Long-termmemory
Attention Encoding
Retrieval
Forgetting ForgettingForgetting
Sensory Memory
• Stores all the stimuli that register on the senses
• Lasts up to three seconds• Two types
– Iconic memory• Visual• Usually lasts about 0.3
seconds• Sperling’s tests (1960s)
– Echoic memory (we’ll come back to this)
Sensory
InputSensory Memory
Sperling’s Experiment
• Presented matrix of letters for 1/20 seconds– Report as many letters as
possible
• Subjects recalled only half of the letters
• Was this because subjects didn’t have enough time to view entire matrix? – No
• How did Sperling know this?
Sperling’s Iconic Memory Experiment
Sperling’s Iconic Memory Experiment
Sperling’s Iconic Memory Experiment
Sperling’s Iconic Memory Experiment
Sperling’s Experiment
• Sounded low, medium or high tone immediately after matrix disappeared– Tone signaled 1 row to
report
– Recall was almost perfect
• Memory for images fades after 1/3 seconds or so, making report of entire display hard to do
High
Medium
Low
Sensory Memory
• Echoic memory– Sensory memory for auditory input
that lasts only 2 to 3 seconds
• Why do we need sensory memory?
Short-term Memory
• Function– Conscious processing of information– Attention is the key
• Limits what info comes under the spotlight of short-term memory at any given time
• AKA working memory
Working orShort-term
Memory
Sensory
Input
Sensory Memory
Attention
Memorize the following list of numbers:
1 8 1 2 1 9 4 1 1 7 7 6 1 4 9 2 2 0 0 1
Write down the numbers in order.
Now, try again…
1812 1941 1776 1492 2001
Short-term Memory
• Limited capacity– Can hold 7 ± 2 items for about 20 seconds– Maintenance rehearsal
• The use of repetition to keep info in short-term memory
• CHUNK– Meaningful unit of information– Without rehearsal, we remember 4 ± 2 chunks– With rehearsal, we remember 7 ± 2 chunks– Ericsson & Chase (1982)
89319443492502157841668506120948888568772731418610546297480129497496592280
Long-term Memory
Working orShort-term
Memory
Sensory
Input
Sensory Memory
AttentionLong-term
memory
Retrieval
• Once information passes from sensory to short-term memory, it can be encoded into long-term memory
Encoding
Long-term memory - Encoding
• Elaborative rehearsal– A technique for transferring information into
long-term memory by thinking about it in a deeper way
• Levels of processing– Semantic is more effective than visual or
acoustic processing– Craik & Tulving (1975)
• Self-referent effect– By viewing new info as relevant to the self, we
consider that info more fully and are better able to recall it
Long-term memory
• Procedural (Implicit)– Memories of behaviors, skills, etc.
• Demonstrated through behavior
• Declarative (Explicit)– Memories of facts
• Episodic – personal experiences tied to places & time
• Semantic – general knowledge– Semantic network
Semantic Networks
Red
Fire
Cherry
Roses
Fire Engine
Apples
House
Green
Flowers
Daisies
Yellow
Orange
Truck
Bus
Ambulance
Sunrise
Sunsets Clouds
Retrieval
• Retrieval– Process that controls flow of information
from long-term to working memory store
• Explicit memory– The types of memory elicited through
the conscious retrieval of recollections in response to direct questions
• Implicit memory– A nonconscious recollection of a prior
experience that is revealed indirectly, by its effects on performance
Retrieval – Explicit Memory
• Free-recall test– A type of explicit memory task in which a
person must reproduce information without the benefit of external cues
• Recognition task– A form of explicit memory retrieval in which
items are presented to a person who must determine if they were previously encountered
• Retrieval failure– Tip-of-the-tongue (Brown & McNeill)
Retrieval – Explicit Memory
• Context-Dependent Memory– We are more successful at retrieving
memories if we are in the same environment in which we stored them
• State-Dependent Memory– We are more successful at retrieving
memories if we are in the same mood as when we stored them
Retrieval – Implicit Memory
• Showing knowledge of something without recognizing that we know it
• Research with amnesics• Déjà vu
– The illusion that a new situation is familiar
• Eyewitness testimony– Eyewitness transference
• Unintentional plagiarism
Forgetting
If we remembered everything, we should on most occasions be as ill off as if we remembered nothing.
William James• Lack of encoding
– Often, we don’t even encode the features necessary to ‘remember’ an object/event
• Decay– Memory traces erode with the passage of time– No longer a valid theory of forgetting– Jenkins & Dallenbach (1924)
Interference theory
• Forgetting is a result of some memories interfering with others– Proactive interference
•Old memories interfere with ability to remember new memories
– Retroactive interference•New memories interfere with ability to
remember old memories
– Interference is stronger when material is similar
Forgetting
• Repression– There are times when we are unable
to remember painful past events– While there is no laboratory
evidence for this, case studies suggest that memories can be repressed for a number of years andrecovered in therapy
Memory Construction
• Schema theory– Preconceptions about persons, objects, or
events that bias the way new information is interpreted and recalled
• Misinformation effect– The tendency to incorporate false postevent
information into one’s memory of the event itself
• Illusory memories– People sometimes create memories that are
completely false
Improving Memory
• Practice time– Distribute your studying over time
• Depth of processing– Spend ‘quality’ time studying
• Verbal mnemonics– Use rhyming or acronyms to reduce
the amount of info to be stored
Improving Memory
• Method of loci– Items to be recalled are mentally placed in
familiar locations
• Interference– Study right before sleeping & review all the
material right before the exam– Allocate an uninterrupted chunk of time to
one course
• Context reinstatement– Try to study in the same environment &
mood in which you will be taking the exam